sky2: in free_buffers() do proper checks before call of rx_clean()

[Lino Sanfilippo <LinoSanfilippo@gmx.de>]

In sky2_open() free_buffers() is called in case that alloc_buffers() failed.
Here we do the check for sky2->rx_le too late, since we already called
rx_clean() which accessed rx_le. Furthermore we lack a check for sky2->rx_ring
which is also accessed by rx_clean().

With this patch both sky2->rx_le and sky2->rx_ring are checked before
alloc_buffers() is called.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
---
 This applies against 3.3

 drivers/net/ethernet/marvell/sky2.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/marvell/sky2.c b/drivers/net/ethernet/marvell/sky2.c
index 760c2b1..3e3eda6 100644
--- a/drivers/net/ethernet/marvell/sky2.c
+++ b/drivers/net/ethernet/marvell/sky2.c
@@ -1628,9 +1628,10 @@ static void sky2_free_buffers(struct sky2_port *sky2)
 {
 	struct sky2_hw *hw = sky2->hw;
 
-	sky2_rx_clean(sky2);
-
 	if (sky2->rx_le) {
+		if (sky2->rx_ring)
+			sky2_rx_clean(sky2);
+
 		pci_free_consistent(hw->pdev, RX_LE_BYTES,
 				    sky2->rx_le, sky2->rx_le_map);
 		sky2->rx_le = NULL;
-- 
1.7.2.5